Glass Armonica

The rim's vibration (all families, n = 2…6) in slow motion, hugely exaggerated. The finger holds a radial node under it; the dots are the irregularity's axes, which the turning glass carries past the finger.

Slip speed of the glass under the skin over the last 21 ms. Flat on zero = stuck: once the bowl speaks, the skin sticks and slips once per cycle.

A bowl needs a moment to speak: its line grows in after the finger lands, warbles at the treadle's rate, and keeps ringing after the finger lifts.

Dashed: the two members in the bowl's frame (split by its irregularity). Solid: where a free, spinning bowl rings in the room (Bryan precession ± the pattern's rotation).